Hypertension

Notes

Definition & classification

Hypertension refers to a persistent elevation of arterial blood pressure

Prevalence is 30% in the UK (defined as adults with BP >140/90 mmHg). It is higher in men than in women before 60 years of age, but equal after this point.

Hypertension is a major risk factor for MI, stroke and chronic kidney disease (CKD). It is classified into ‘stages’ to help guide management.

Aetiology

The majority of hypertension is essential (primary), however in a significant number of cases there may be a secondary cause or contributory factor.

Aetiology of HTN

Primary - 95%

  • No identifiable underlying cause.

Secondary - 5%

  • Endocrine:
    • Primary aldosteronism (increasingly recognised as a major cause of hypertension, see notes )
    • Phaeochromocytoma
    • Cushing’s disease (see notes)
    • Acromegaly (see notes)
  • Renal
    • Renovascular disease (e.g. atheromatous, fibromuscular dysplasia)
    • Intrinsic renal disease (e.g. CKD, AKI, glomerulonephritis)
  • Drugs
    • Glucocorticoids
    • Oral contraceptives
    • SSRIs
    • NSAIDs
    • EPO
  • Coarctation of the aorta (consider in children / young adults with hypertension).

NOTE: This is an evolving area. It is now thought that a greater proportion of cases of hypertension have a secondary cause. Some studies indicate primary aldosteronism is responsible for 5-15% of cases of hypertension. 

Clinical features

Hypertension is typically asymptomatic. However, signs and symptoms may reflect underlying end-organ damage or a potential secondary cause.

Symptoms

  • Palpitations
  • Angina
  • Headaches
  • Blurred vision
  • New neurology (e.g. limb weakness, paraesthesia)

Signs

  • New neurology (e.g. limb weakness, paraesthesia)
  • Retinopathy
  • Cardiomegaly
  • Arrhythmias 
  • Proteinuria
  • Uraemia

HTN clinical features

Hypertensive retinopathy

Hypertension may cause progressive retinal microvascular changes

These changes have been classified by the Keith-Wagener Barker (KWB) grades:

  • Grade 1: Generalised arteriolar narrowing (silver wiring).
  • Grade 2: Focal narrowing and arteriovenous nipping.
  • Grade 3: Retinal haemorrhages, cotton wool spots (retinal nerve fibre layer micro-infarcts leading to exudation of axoplasmic materials). 
  • Grade 4: Papilloedema

Grade 4 may indicate malignant hypertension requiring admission and immediate management. Recently there has been a move away from the KWB grades with a new three stage system proposed.

Hypertensive retinopathy

Investigations

In the following patients underlying causes should be thoroughly excluded:

  • Age < 40 years
  • Reduced eGFR (suggestive of renal disease)
  • Proteinuria or haematuria (suggestive of renal disease)
  • Hypokalaemia and hypernatraemia (suggestive of Conn’s syndrome)
  • Hypertension that is sudden onset, variable or worsening.

Bedside

  • Observations
  • Blood pressure
  • Urinalysis
  • ECG
  • Direct ophthalmoscopy

Bloods

  • FBC
  • U&Es
  • Fasting glucose
  • Cholesterol (CVS risk)

Special tests

  • Ambulatory BP monitoring
  • Renal USS
  • Endocrine tests (e.g. aldosterone: renin ratio, if indicated)

Diagnosis

NICE now recommends the use of ambulatory BP measurements (ABPM) for the diagnosis of Stage 1 & 2 hypertension.

If clinic BP is 140/90 mmHg or higher, ABPM is used to confirm the diagnosis (except in Stage 3 hypertension, in which immediate treatment is initiated). With ABPM, at least two measurements an hour are taken during the patient's usual waking hours (e.g. 8 am - 10 pm). The average value of these measurements is used to confirm the diagnosis.

Stage 1

  • ABPM ≥ 135/85, or
  • Clinic BP ≥ 140/90
  • Plus one or more of the following:
    • End organ damage (e.g. hypertensive retinopathy, left ventricular hypertrophy)
    • CVS disease
    • Renal disease
    • Diabetes
    • 10 year CVS risk > 20% (e.g. Framingham risk calculator)

Stage 2

  • ABPM ≥ 150/95, or
  • Clinic BP ≥ 160/100

Stage 3

  • Clinic BP ≥ 180/110

Management

​Management of hypertension is based upon NICE guidelines.

Modifiable risk factors

Lifestyle modification & patient education are important in treating hypertension.

  • Offer advice that targets the patient's modifiable risk factors.
  • Discourage excessive caffeine and alcohol, if appropriate offer smoking cessation advice.
  • Consider the need for anti-platelets or a statin.

Whom to treat

Antihypertensive drug therapy is initiated in patients:

  • aged < 80 years with stage 1 hypertension and with one of the following; end organ damage, cardiovascular disease, 10-year cardiovascular risk factor above 20% or renal disease,
  • of any age with stage 2 hypertension
  • of any age with stage 3 hypertension (immediately)

Medical therapy

Hypertension is managed in a step-wise fashion. If blood pressure is not controlled with each step, medication should be reviewed to ensure that the treatment is optimal before moving onto the next step.

For people aged > 80 years, offer the same anti-hypertensive therapies as for people aged 55-80 years, however take into consideration comorbidities.

Management of HTN

Blood pressure targets

  • Patients < 80 years: 140/90 mmHg
  • Patients > 80 years: 150/90 mmHg

Those with renal disease and proteinuria or diabetes should target a BP of <130/80.

Hypertensive emergencies

Hypertensive emergencies occur when high BP results in acute end-organ damage.

The term malignant (or accelerated) hypertension is typically reserved for when papilloedema is present and is defined by NICE as:

A BP >180/110 with signs of papilloedema and/or retinal haemorrhage.

It is a severe condition resulting in neurological, renal and cardiac damage, requiring admission and immediate management.

Treatment attempts to reduce BP over 24-48hrs. This is to prevent hypoperfusion. Changes may have occurred to autoregulatory mechanisms of blood pressure control. Therefore, a rapid reduction in blood pressure, even to normal levels, may result in profound organ hypoperfusion.

Therapies include:

  • IV Nitroprusside (a nitric oxide releasing drug), labetalol is an alternative.
  • Phentolamine (alpha-adrenergic antagonist) also used in phaeochromocytoma crisis.

 

Pulsenotes uses cookies. By continuing to browse and use this application, you are agreeing to our use of cookies. Find out more here.